1. Field
This invention relates to compound archery bows and more particularly relates to the rigging for such bows. It is specifically directed to an improved system for connecting the cable elements of such a rigging to the eccentric elements of such a rigging.
2. State of the Art
Compound archery bows are currently available in a variety of configurations. They are most generally configured substantially as illustrated in the original patent to Allen, U.S. Pat. No. 3,486,495. As so configured, the compound bow includes a handle, a pair of limbs extending from opposite ends of the handle to present spaced opposed limb tips, and a pair of eccentric elements rotatably mounted on eccentric axes associated with the respective limb tips. The eccentrics and limb tips are interconnected by a rigging system which includes the eccentrics and stretches of cabling or similar tension runs constructed of aircraft cable or bowstring materials. The cabling includes a central stretch, generally including the bowstring, and a pair of end stretches. Each end stretch extends from attachment at one limb tip across the bow handle to attachment with the eccentric member mounted at the opposite limb tip.
Although a great deal of development has occurred with respect to the specific configuration of eccentric elements utilized with compound bows of modern design, most of the currently available eccentric elements include a take-up cam and a let-off cam in approximately side-by-side relation. Each of those cams conventionally carries a cable receiving peripheral groove about at least a portion of its perimeter. The groove should proceed around that portion of the perimeter which is contacted by cable at any stage of the draw of the nocking point of the bowstring from its at-rest position to its fully drawn position. An axle journal, which may be a simple hole or a hole with an appropriate bushing in place, is provided approximately transverse the take-up and let-off cams at a location eccentric with respect to the geometric center of the eccentric element. The terms "take-up" and "let-off" refer to winding or unwinding, respectively, of stretches of the cabling.
Compound bows include a rigging whereby each of the eccentrics of a matched pair of eccentrics is connected to an end stretch, typically formed of aircraft cable or similar material. Each end stretch cable includes a let-off segment which extends from a let-off groove of the let-off cam and a take-up cable segment extending from a take-up groove of the take-up cam on the opposite side of the eccentric element. Thus, in assembly, the end stretch cable must be inserted into a bore or comparable cable passageway extending from one of the peripheral grooves through the interior of the eccentric to exit from a corresponding cable passageway communicating with the opposite peripheral groove.
The free end of the take-up portion of the cable is adapted for connection to structure associated with one of the limb tips. In most instances it is provided with a large loop which may be connected to the limb tip by placement over an axle or within a clamp carried near the limb tip. Similarly, the let-off portion of the end stretch cable is specially adapted for attachment to a bowstring. Typically, it is so adapted by carrying a special fixture called a "tear drop" at its end. Both this tear drop fixture and any corresponding fixture carried by the end of the take-up portion of the cable require special tools and techniques for proper attachment. Special techniques and materials are also required to fashion a reliable loop in the end of a cable portion. Accordingly, it is beyond the capabilities of a typical archer to replace the worn or broken cables of a compound archery bow without professional help.
Because it is necessary for the cable to be inserted through the eccentrics prior to fastening the loop or fixtures at the end of the take-up and let-off portions extending from the eccentric, it has not heretofore been feasible in most instances for an archer to order replacement cables from a supplier without ordering an entire rigging, including the eccentrics. The other alternative available to an archer is to return the eccentrics of his bow to a manufacturer or a pro shop for the professional replacement of the end stretch cables. Replacement of cables in the field following a cable breakage has been impractical and unfeasible.
It has long been recognized that an end stretch may be discontinuous; i.e., provided in segments. Individual segments may be connected individually to an eccentric. Such arrangements have generally been factory assembled by means requiring professional assembly techniques. In other instances, individual let-off and take-up segments of an end stretch cable have been connected to an eccentric by means which are inherently dangerous. Thus, in the event of a cable breakage, individual components of such systems may actually be propelled as hazardous projectiles. Some modern rigging systems are particularly susceptible to breakage, in which event "tear drops" and similar fixtures are hazardous.
Some modern cable systems deliberately avoid the use of metal cables for the end stretches. The bowstring materials used in such systems tend to stretch and twist. Thus, it is difficult to properly time peep sights carried by the central stretch.
There remains a need for a rigging system by which the end stretch cables may be replaced by an archer without the need for professional assistance. There also remains a need for a less hazardous rigging system generally. There also remains a need for such a rigging which retains the ability to utilize metal cable end stretch segments.